NOTES for Gen 3:4
Most questions usually arise in connection with what it means to be "knowing good and evil." How can one judge the moral act of a person who does not know, as Adam and Eve apparently did not before the fall, what good and evil are? We do not judge a child; we explain that he has acted badly, but even in a strictly legal sense we do not judge him, because we understand that he simply does not yet know what good and evil are.
But here the matter is something entirely different. To imagine the situation in that way is fundamentally wrong. In reality, the serpent offers Adam and Eve the possibility of deciding what good and evil are. "To know" (Hebrew "yada") often means "to be able," "to master," "to possess." The concept of what is good and what is evil lies at the foundation of creation; it is a meaning-forming or structural part of the universe. That is precisely why it says "like gods": they are being offered the chance to build their own little world, separate, where they would be masters over themselves.
And after that everything is very simple. Take one step in the wrong direction, and then one thing catches onto another. It is much easier to abstain from temptation altogether than, after thinking, "I will allow myself a little," to struggle later with its strength multiplied tenfold. Such is the law of every sin.